Examine the various senses and the differences between them in a good dictionary, such as this one of Lewis and Short, and read all the books they cite! Some senses are identical between words, some near identical, some different (and some opposites, of course). Oh, if that wasn't hard enough for you, the senses of a single word can also change and vary over time and between places, so you need to check the dates and places of the authors cited. Otherwise, just do the best you can, until someone points out your mistakes. Sensibus variis et discriminibus mutuis in dictionario bono ut hoc apud Lewis et Short studeas. Tunc omnes libros quos citant legas! Aliae significationes inter verbos synonyma sunt, aliae similes, aliae diversae (aliae antonyma, certé). Hui! Si id tibi non satìs difficile est, memoriâ tene sensus singuli verbi per tempore et inter locos variare mutareque posse. Ideò, te oportet et locos nativos et aetates auctorum citatorum notare. Aliter, apertè fac pro viribus antequàm nescio quis te corrigit.

I wouldn't worry too much about the finer points of diction now. Of course, it's important to know when there are clear differences in usage between words you're writing. However, often it comes down to personal choice and there is rarely a "right" answer with writing/translation. I might use "explicate" or "explain" in an English essay interchangeably with no difference in meaning, and Latin authors assuredly did the same thing with their synonyms. Of course, the more technical the writing, the more nuanced certain words can become (like medieval scholastic philosophy) but that's another matter.